1. A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test
- Author
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Hasler, David, Anagnostopoulou, Pinelopi, Nyilas, Sylvia, Latzin, Philipp, Schittny, Johannes, Obrist, Dominik, Anagnostopoulou, Pinelopi [0000-0003-2597-8016], Latzin, Philipp [0000-0002-5239-1571], and Obrist, Dominik [0000-0002-6062-9076] more...
- Subjects
Lung Diseases ,Male ,0301 basic medicine ,Pulmonology ,Physiology ,Respiratory System ,Pulmonary Function ,Pulmonary function testing ,0302 clinical medicine ,Medicine and Health Sciences ,Biomechanics ,Expiration ,Biology (General) ,610 Medicine & health ,Lung ,Flow Rate ,Ecology ,Chemistry ,Physics ,Simulation and Modeling ,Classical Mechanics ,Washout ,Thorax ,respiratory system ,Respiratory Function Tests ,Trachea ,medicine.anatomical_structure ,Computational Theory and Mathematics ,Modeling and Simulation ,Physical Sciences ,Pleurae ,Breathing ,Female ,Anatomy ,Research Article ,Tissue Mechanics ,Adolescent ,QH301-705.5 ,Biophysics ,Fluid Mechanics ,Respiratory physiology ,Research and Analysis Methods ,Models, Biological ,Continuum Mechanics ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Genetics ,medicine ,Humans ,Respiratory Physiology ,Fluid Flow ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Pulmonary Gas Exchange ,Computational Biology ,Biology and Life Sciences ,Fluid Dynamics ,respiratory tract diseases ,030104 developmental biology ,Volume (thermodynamics) ,Airway ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
The multiple-breath washout (MBW) is a lung function test that measures the degree of ventilation inhomogeneity (VI). The test is used to identify small airway impairment in patients with lung diseases like cystic fibrosis. However, the physical and physiological factors that influence the test outcomes and differentiate health from disease are not well understood. Computational models have been used to better understand the interaction between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the tracer gas washout test in a whole. Thus, our aim was to create a lung model that simulates the entire MBW and investigate the role of lung morphology and tissue mechanics on the tracer gas washout procedure. To this end, we developed a multi-scale lung model to simulate the inert gas transport in airways of all size. We then applied systematically different modifications to geometrical and mechanical properties of the lung model (compliance, residual airway volume and flow resistance) which have been associated with VI. The modifications were applied to distinct parts of the model, and their effects on the gas distribution within the lung and on the gas concentration profile were assessed. We found that variability in compliance and residual volume of the airways, as well as the spatial distribution of this variability in the lung had a direct influence on gas distribution among airways and on the MBW pattern (washout duration, characteristic concentration profile during each expiration), while the effects of variable flow resistance were negligible. Based on these findings, it is possible to classify different types of inhomogeneities in the lung and relate them to specific features of the MBW pattern, which builds the basis for a more detailed association of lung function and structure., Author summary Obstructive lung diseases, like cystic fibrosis or primary ciliary dyskinesia, lead to inhomogeneous ventilation. The degree of observed inhomogeneity represents a clinical measure for the progression of the disease. The multiple-breath washout (MBW) is a lung function test that measures this inhomogeneity in the lung. However, the factors that influence the results of the test and differentiate between health and disease are not well understood. Computational models help us to understand better the relation between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the MBW test in whole. Our aim was to create a lung model that simulates the entire MBW test and study the role of lung structure and tissue mechanics on the washout procedure. We developed a multi-scale lung model to simulate the inert gas transport in all airways including the gas exchange area. Our model offers the opportunity to understand the ventilation distribution in the healthy lung. It can also mimic certain patterns of lung disease by applying modifications in mechanical properties out of the physiological limits. Thus, it can be used to study MBW characteristics in health and disease. more...
- Published
- 2019
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